We report density functional calculations using the full-potential linearized muffin-tin orbital method on early first row transition metal doped Silicon Carbide in both cubic (3C) and hexagonal (4H) polytypes. The energy levels in the gap for Ti, V and Cr are in good agreement with the available photoluminescence experiments. Our calculation shows that the Ti impurity is active for 4H but not for 3C, while V and Cr impurities are active for both polytypes. The magnetic interactions are very different for Cr and Mn. Cr shows a very local exchange interaction that decays rapidly, which is similar for different polytypes and different sites. The exchange interaction for Mn is quite long range and is very sensitive to the location of the Mn pairs.